ignore words should not be removed from path tokens

When creating an automated path alias that uses the path token of a related node ignore words are being removed in pathauto_cleanstring.

If you had a node (node1) with a path alias set to /the-way and a bunch of nodes (sub-node) that refer to it and try to use the node1 path in their automated path alias ([node1-path]/[sub-node-title-raw]). A sub-node with "test" as the title would end up with an alias of /-way/test, instead of /the-way/test.

The pathauto_cleanstring function already takes a parameter to allow path tokens to specify that slashes should not be removed, so it should have another parameter to specify whether or not to remove the ignore words.